Fix licenses in headers to pass Chromium's checklicenses tool.

This is a re-landing of the changes in https://pdfium.googlesource.com/pdfium/+/6387aff
which were lost during a libopenjpeg library roll.

TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/661463003
Fix standalone build on Linux and Mac.

BUG=423883
R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/663633002
Make DEPS not add an extra pdfium directory.

This makes gclient config and gclient sync work.

BUG=423896
TBR=aneeshm@chromium.org

Review URL: https://codereview.chromium.org/656353002
Added Target recognition and possibility to build for i386.

Added Target recognition and possibility to build for i386.
Also upgrade compiler keys
Merge remote-tracking branch 'origin/master' into light_version